Preheat the oven to 350°Line 15-cup muffin cups with paper liners.

In a large bowl, beat the oil, butter, and sugar together on medium-high speed until light and fluffy, about 5 minutes. Add the eggs, one at a time, mixing for 20 seconds after each addition. Beat in the vanilla.

Combine the flour, baking powder, baking soda, and salt in a medium bowl. Stir with a whisk and add half to the butter mixture. Beat on low speed until the flour is almost fully incorporated.

Add the buttermilk followed by the remaining flour mixture and beat on low until just combined. Take care not to over mix.

Gently fold in the chopped strawberries.

Fill each muffin cup ⅔ of the way full. Bake for 14-18 minutes or until a toothpick inserted into the center comes out with a few moist crumbs attached. Take care to not over-bake.

Cool for 10 minutes. Transfer to a wire rack and cool completely before frosting.

Add the strawberries to a food processor or blender and process until smooth. Add strawberry puree to a small saucepan. Cook over medium-high heat, stirring occasionally until the puree has reduced to 2-3 tablespoons, about 10 minutes.

Remove from heat and transfer to a small bowl. Allow the puree to cool completely, stirring every so often.

Once the puree has cooled, add the butter to the bowl of a stand mixer fitted with the paddle attachment or to a large bowl using an electric hand mixer. Beat on medium-high speed until creamy and pale in color, about 5 minutes. Stop to scrape down the sides of the bowl as needed.

Add the vanilla, salt, and half the confectioners' sugar and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.

Add the puree and beat at medium-low speed until fully mixed in.

Add the remaining confectioners' sugar and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.

Keep cupcakes covered tightly and store them in the refrigerator for up to 3 days. Serve at room temperature